Ultrafine PtCo bimetallic nanoparticles loaded carbon nanoflowers for high performance hydrogen evolution reaction catalysis

A facile and robust strategy is proposed for the fabrication of three-dimensional (3D) carbon nanoflowers (CNFs) based on the intramolecular cyclization-induced self-assembly (ICISA) mechanism of poly(amic acid) (PAA), which efficiently incorporates ultrafine platinum/cobalt (PtCo) bimetallic nanoparticles to form PtCo/CNFs for high performance hydrogen evolution reaction (HER) catalysis in alkaline media. The amphiphilic PAA is synthesized by the condensation polymerization of p -phenylenediamine and pyromellitic dianhydride, which self-assembles into 3D nanoflowers driven by the ICISA. Upon pyrolysis in an inert atmosphere, the structural features of the nanoflowers can be well inherited due to the unique thermal property of PAA, and ultrafine PtCo bimetallic nanoparticles with a size of 1.7 ± 0.5 nm can be efficiently loaded. The XPS shows the electron transfer between Pt, Co atoms and the CNFs, leading to an overpotential of 27.3 mV at 10 mA cm −2 and a mass activity of 4.73 A mg Pt −1 for HER catalysis, superior to commercial Pt/C. Overall, the high porosity, optimized electronic structure and full exposure of active sites, significantly enhance the catalytic performance of the catalyst in alkaline electrolytes.